The present invention is generally directed to generation of diffuse infrared light. More particularly, the invention is directed to a system for illuminating an object with diffuse infrared light and producing a video image of the object based on reflected infrared light.
Some medical procedures and treatments require a medical practitioner to locate a blood vessel in a patient""s arm or other appendage. This can be a difficult task, especially when the blood vessel lies under a significant deposit of subcutaneous fat. The performance of previous imaging systems designed to aid in finding such blood vessels has been lacking.
Therefore, a system for enhancing the visual contrast between subcutaneous blood vessels and surrounding tissue is needed.
The foregoing and other needs are met by an imaging system for viewing body tissue under diffuse infrared illumination to enhance visibility of subcutaneous blood vessels. The imaging system includes an illumination system for illuminating the body tissue with infrared light that arrives at the body tissue from a plurality of different illumination directions. Thus, the illumination system provides diffuse infrared light to the body tissue. The imaging system also includes a video imaging device for viewing the body tissue, for receiving the diffuse infrared light reflected from the body tissue, and for generating a video image of the body tissue based on the diffuse infrared light reflected from the body tissue.
Using the invention described herein, subcutaneous blood vessels that are difficult or impossible to see under white light or under non-diffuse infrared light can be easily seen in the video image, where the subcutaneous blood vessels appear as dark lines against a lighter background of surrounding flesh.
In preferred embodiments of the invention, the illumination system includes an infrared light source for generating the infrared light and a light diffusing structure for diffusing the infrared light. The diffusing structure has an input aperture for receiving the infrared light from the infrared light source, and multiple interior reflecting surfaces. The reflecting surfaces reflect the infrared light multiple times and in multiple directions, thereby producing diffuse infrared light. The diffusing structure also has an output aperture for receiving the diffuse infrared light reflected from the plurality of reflecting surfaces and for emitting the diffuse infrared light toward the body tissue. The system further includes a video imaging device for receiving the diffuse infrared light reflected from the body tissue and for generating a video image of the body tissue based on the reflected infrared light.
In some preferred embodiments, the diffusing structure includes an elongate outer enclosure having reflective inner surfaces, and an elongate inner enclosure disposed within the outer enclosure. The inner enclosure has reflective outer surfaces facing the inner surfaces of the outer enclosure.
In other preferred embodiments, the invention provides an illumination system for enhancing visual contrast between bright and dark areas of an object as sensed by a direct observer of the object. The system includes an infrared light source for generating infrared light, and a structure for diffusing the infrared light. The diffusing structure has an input aperture for receiving the infrared light from the infrared light source, and multiple reflecting surfaces for reflecting the infrared light multiple times and in multiple directions, thereby producing diffuse infrared light. The diffusing structure also has an output aperture for receiving the diffuse infrared light reflected from the reflecting surfaces and for emitting the diffuse infrared light toward the object. The system further includes a video imaging device for measuring diffuse infrared light reflected from the object in the form of an image, and for creating a video output signal representative of the image. A video projector receives the video output signal from the video imaging device and projects visible video projector light onto the object, thereby forming a visual image which is representative of the visual image received by the video imaging device. The visual image projected by the video projector illuminates the object from the same perspective that the video imaging device views the object. Thus, features of the projected visual image overlay the corresponding features of the object. The system includes a filter for distinguishing between the diffuse infrared light and the visible video projector light. The filter prevents the visible video projector light from reaching the video imaging device while allowing the diffuse infrared light reflected from the object to reach the video imaging device. Thus, the filter eliminates positive feedback which would degrade the desired visual effect.
In yet another aspect, the invention provides a method for viewing body tissue under infrared illumination to enhance visibility of subcutaneous blood vessels. The method includes the step of providing infrared light to the body tissue from multiple different illumination directions, thereby illuminating the body tissue with diffuse infrared light. The method also includes viewing the body tissue from a viewing direction using a video imaging device, and generating a video image of the body tissue based on diffuse infrared light reflected from the body tissue. Using the video image of the body tissue, the subcutaneous blood vessels may be found.